Problem 17 - Objective Biology for NEET

Question

Which of the following is not secreted by exocrine glands? (a) Earwax (b) Oil (c) Milk (d) None of these

Step-by-Step Solution

Answer

(d) None of these

Step 1: Understand Exocrine Glands

Exocrine glands are glands that produce and secrete substances onto an epithelial surface by way of a duct. Examples of exocrine glands include sweat, salivary, mammary, ceruminous, lacrimal, sebaceous, and mucous.

Step 2: Match Options with Exocrine Secretions

(a) Earwax - This is secreted by ceruminous glands, a type of exocrine gland. So, this option is incorrect. (b) Oil - This is secreted by sebaceous glands, another type of exocrine gland. So, this option is also incorrect. (c) Milk - This is secreted by mammary glands, which are, once again, a type of exocrine gland. So, this option is again incorrect.

Step 3: Choose the Correct Option

Having checked all options (a), (b) and (c), it can be concluded that all of these substances are secreted by exocrine glands. Hence the correct answer to the question, 'Which of the following is not secreted by exocrine glands?' is (d) None of these.

Key Concepts

Exocrine Gland Secretions

Exocrine glands play an essential role in the human body by producing and secreting various substances directly to the target areas via ducts. These secretions can be anything from enzymes necessary for digestion to sweat used in temperature regulation.

Unlike endocrine glands, which secrete hormones into the bloodstream, exocrine glands have specific locations where their secretions are needed. Examples include the salivary glands in the mouth, which facilitate the initial digestion of food, or the pancreas, which releases pancreatic juice containing digestive enzymes into the small intestine. Understanding these gland functions helps students appreciate the intricate processes that keep the human body functioning.

Ceruminous Glands Earwax

Earwax, also known as cerumen, is a naturally occurring substance that provides protection for the inner ears. The ceruminous glands in the ear canal secrete this waxy material.

Earwax serves multiple purposes; it keeps the ear canal lubricated, repels water, and functions as a barrier to trap dust, microorganisms, and other debris, preventing them from reaching the eardrum. Although sometimes viewed as a nuisance, earwax is a crucial part of our ear's defense system.

Sebaceous Glands Oil

Sebaceous glands are found all over the skin's surface except for the palms of the hands and soles of the feet, and they secrete an oily substance called sebum.

Sebum is important for waterproofing and moisturizing the skin and hair, keeping them from becoming too dry or brittle. It also has antibacterial properties, which help protect the skin from infections. Hormonal changes can influence the activity of sebaceous glands, which is why they often become more active during puberty, leading to acne.

Mammary Glands Milk

Mammary glands are specialized organs in female mammals that are responsible for producing milk to nourish newborns. These glands are activated during pregnancy and subsequent childbirth.

The production and secretion of milk, called lactation, provide essential nutrients, antibodies, and enzymes to the infant, playing a vital role in its growth and immune defense. The complex composition of milk varies across different species but is always tailored to meet the specific needs of the offspring.